Current drivers (also referred to as current sources) can be used to provide current for a variety of loads including valves, motors, explosive charges, lighting, resistive loads, etc. For instance, a current driver can be used to provide a constant current to a Light Emitting Diode (LED) to minimize variations in a brightness of the LED when the source voltage varies. When current drivers are used to operate valves, the current drivers can utilize a higher initial current to actuate the valve followed by a lower subsequent current to hold the valve in the desired position. This type of two-stage operation can reduce the power requirements of the current driver, which can provide power efficiency benefits to a system that includes valves.
Since valves include an inductive component of the total load seen by the current driver, additional power efficiencies can be gained by operating the current driver similar to a DC-DC converter, with the inductance of the valve operating to average a switching waveform of the supply voltage applied to the valve. This allows the current driver to vary the average current applied to the valve by varying a duty cycle or frequency of the switching waveform.
Often, current drivers are utilized in various space or military applications such as missiles, manned or unmanned propulsion vehicles, and spacecraft. In these applications, current drivers are used to control fuel valves, detonate ordinance, etcetera, and are expected to operate with a high degree of reliability and with a certain measure of recoverability in cases of circuit faults. However, current drivers can sometimes experience short circuit conditions which can permanently damage the drivers and compromise the performance of the missiles, manned or unmanned propulsion vehicles, or spacecraft that utilize current drivers.